Cooler for electronic devices

ABSTRACT

A cooler for electronic devices provides cool air to the inlet sides of the heat sink by using a radial blower with blades located around air outlets of the heat sink. This blower is driven by a brushless DC electric motor. The motor has an opening in the center allowing for the transfer of incoming air to the center of the heat sink. Th rotors outer circumferential arrayed poles are rigidly secured to the frame of the radial blower. The stator of the motor is rigidly secured to the heat sink and has an opening in its center. The stator comprises circumferential arrayed coils on circuit board material. When the current flows through the stator coils, the coils acquire a magnetic polarity. The poles of the rotor and stator coils attract and repel depending on the polarities. The cool air comes simultaneously from opposite sides of the heat sink. For this reason the heat sink has a divider located approximately in the middle of the heat sink fins. The blades of the radial blower are located around the air outlets on the heat sink. Because the ambient air is drawn in from both sides of the heat sink the air path length through the heat sinks channels is effectively halved. This results in an increased cooling ability for the heat sink because of the increase in temperature differentials.

FIELD OF THE INVENTION

[0001] The present invention relates generally to cooling devices and inparticular, to cooling devices used for removing heat from electroniccomponents by means of a gas flow, in particular air produced by ablower.

BACKGROUND OF THE INVENTION

[0002] During normal operation many electronic components generatesignificant amounts of heat. If this heat is not continuously removedthe electronic component may overheat resulting in damage and/or areduction in operating performance. In order to avoid such problemscooling devices are often used in conjunction with these components.

[0003] One such cooling device is a fan assisted heat sink. In such adevice a heat sink is formed from a material, such as aluminum, whichreadily conducts heat. The heat sink is usually placed on top of and inphysical contact with the component.

[0004] One method of increasing the cooling capacity of these heat sinksis by including a plurality of cooling fins that are physicallyconnected to the heat sink. These fins serve to increase the surfacearea of the heat sink and, thus maximize the transfer of heat from theheat sink to the surrounding atmosphere. In this manner the heat sinkdraws heat away from the component and transfers the heat into thesurrounding air.

[0005] In order to further enhance the cooling capacity of a heat sinkdevice an electrically powered blower (an axial fan may serve as theblower) is often mounted within or on top of the heat sink. In operationthe fan forces air to move past the fins of the heat sink, thus coolingthe fins by enhancing the transfer of heat from the fins into thesurrounding atmosphere. As the fins are cooled heat can be drawn fromthe component into the heat sink at a faster rate. The fan typicallydraws air into the heat sink from the top, passes the air over the fins,and exhausts the air in the vicinity of the bottom. Accordingly, theexhaust air is hotter than that of the intake air.

[0006] There are known devices of this type, for example, U.S. Pat. No.6,196,300 “Heat sink”. The device described in this US patent comprisesan axial fan that produces a flow passing by heat exchanging channels ofthe heat sink. The majority of inlets to the heat exchanging channelsare located just opposite the axial fan's impeller with a certain numberof said channels being placed radially in relation to fan axle.

[0007] To increase the heat exchange area, the heat exchanging channelsare made of spiral-like shape and bent backwards in the direction ofblower rotation. The axial fan produces a sufficiently high airpressure. However, due to the weak airflow in the area adjacent to fanaxle, the conditions for cooling the central part of the heat sinklocated underneath the fan are unfavorable. In this case non-uniformcooling of the heat sink and electronic component will take placeallowing for bad conditions for the heat exchange process.

[0008] Centrifugal blowers are used more rarely in cooling devicedesigns for the purpose of producing airflow.

[0009] Specifically, U.S. Pat. No. 5,838,066 “Miniaturized cooling fantype heat sink for semiconductor device” offers a design employing acentrifugal blower that is installed to the side of the heat sink. Inone particular embodiment of this invention the cooling airflow passesby rectilinear means through the heat exchanging channels of the heatsink.

[0010] However, placement of a centrifugal blower to the side of theheat sink increases the devices size and reduces its effectiveness. Thisis because the location of the centrifugal blower leads to insufficientcoordination between the direction of channel inlets and direction ofairflow supplied from the blower. The loss in airflow energy results inthe reduction of airflow speed in the heat exchanging channels and thereduction of heat exchange efficiency. A portion of energy is alsoexpended as friction against the casing that encloses the blower.

[0011] An invention described in the patent of Japan No 8-195456entitled “Cooler for electronic apparatus”. This device comprises acentrifugal fan enclosed in the casing and installed above the heatexchanging channels that are made divergent. Another heat sink surfaceis made so that the possibility of thermal contact with an electronicdevice is provided for. The inlet of the centrifugal fan faces the heatsink. The fan produces an airflow that passes by the heat exchangingchannels and then gets drawn into the inlet of the centrifugal fan.Since this centrifugal fan operates by drawing air in through the heatsink, there is an area in the central part of the heat sink thatreceives poor air circulation. Adding to this problem, the airflow firstpasses through the elongated heat exchanging channels gathering heatalong the way from the channels surfaces. As the air approaches thecentral part of the heat sink its cooling ability is decreased due tothe reduced temperature differential between the preheated channel airtemperature and the surface temperature at the center of the heat sink.This results in inefficient cooling of the heat sink's central surfacearea and uneven cooling of the heat sink in general. This is the areawhere the electrical component is transferring the most heat to the heatsink and where the greater differential between the two is mostimportant. To help overshadow this problem, one has to increase the fanspower resulting in an increased airflow but not solving the initialproblem. In addition to the heat dissipation problems, the device isconsiderably large due to the centrifugal fans placement above the heatsink. An electric drive is yet placed above the centrifugal fanincreasing the coolers overall size even more.

[0012] Electronic component size has decreased significantly in the pastand this trend of miniaturization will most likely continue in thefuture. Therefore the footprint area of electronic devices (namelyCPU's) is much smaller now and will be even smaller in the future. Thiscreates the problem of first extracting the heat from a very smallsurface area and then transferring this heat, with minimal thermallosses, to the larger heat-dissipating device. Traditional flat heatsinks are unable to extract and dissipate the required heat from thesesmall component footprints.

[0013] It would be desirable to provide a cooling apparatus that wouldovercome these problems associated with the present fan assisted heatsink devices.

SUMMARY OF THE INVENTION

[0014] Accordingly, it is the object, of the present invention, toprovide a cooler that more effectively cools the center of the heat sinkand in doing so ensures a more uniform cooling of the attachedelectronic component.

[0015] It is another object, of the present invention, to provide acooler for electronic components with a reduction in overall size.

[0016] Further, it is the object, of the present invention, to providean electric motor/fan in combination with a heat sink.

[0017] It is another object, of the present invention, to provide acooler for electronic components with increased cooling ability for theheat sink because of the increase in temperature differentials.

[0018] This can be achieved by using a new proposed design. This designprovides cool air to the inlet sides of the heat sink by using a radialblower with blades located around air outlets of the heat sink. Thisblower is driven by a brushless DC electric motor that utilizes a ringtype permanent magnet rotor. This rotor has an opening in the centerallowing for the transfer of incoming air to the center of the heatsink. The rotors outer circumferential arrayed poles are rigidly securedto the frame of the radial blower. The stator of the motor is rigidlysecured to the heat sink and has an opening in its center. The stator iscomposed of circumferential arrayed coils on the circuit board material.When the current flows through the stator coils the coils acquire amagnetic polarity. The poles of the rotor and stator coils attract andrepel depending on the polarities. This action provides for a smoothcontinuous directional motor rotation.

[0019] Another novelty of the present invention is that the cool aircomes simultaneously from opposite sides of the heat sink. Therefore,the heat sink might have a divider located approximately in the middleof the heat sink fins and perpendicular to the axel. The blades of theradial blower are located around the air outlets on the heat sink.Because the ambient air is drawn in from both sides of the heat sink theair path length through the heat sinks channels is effectively halved.This results in an increased cooling ability for the heat sink becauseof the increase in temperature differentials.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The essence of the invention being claimed is explained with theaccompanying drawings in which like reference numerals designate likeparts throughout the thereof and wherein:

[0021]FIG. 1 is an axial sectional view showing a first embodiment ofthe present invention.

[0022]FIG. 2 is an axial sectional view showing a second embodiment ofthe present invention.

[0023]FIG. 2A is a partial axial sectional view of FIG. 2 with anopening to show the electric drive motor of the second embodiment of thepresent invention.

[0024]FIG. 2B is a side view taken along arrow A of FIG. 2A depictingthe rotors relation to the stator board and its coils.

[0025]FIG. 3 is a view taken along arrow B of FIG. 2.

[0026]FIG. 3A is an embodiment of the FIG. 3 with the lower part of theheat sink having square form.

[0027]FIG. 4 is an end view of the heat sink view along arrow C of FIG.2.

[0028]FIG. 5 is a sectional view taken along line I-I of FIG. 2.

[0029]FIG. 6 is a sectional view taken along line II-II of FIG. 2.

[0030]FIG. 7 is a sectional view taken along line III-III FIG. 2.

[0031]FIG. 8 is an axial sectional view showing a third embodiment ofthe present invention.

[0032]FIG. 9 is an axial sectional view showing a fourth embodiment ofthe present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0033] Preferred embodiments of the present invention will be describedin detail below with reference to the accompanying drawings.

[0034] The first embodiment of the present invention is shown in FIG. 1.The cooler includes the central core 1; said central core 1 has acylindrical shape 2 with a flat top surface 3 and a flat bottom surface4. The flat bottom surface 4 is for making direct mechanical contactwith electronic component heat dissipation footprint 6. Said flat bottompart surface 4 and said electronic component heat dissipation footprint6 have about the same shape of contact surfaces. Shape the bottomsurface usually is the same as the electronic component heat dissipationfootprint one.

[0035] The central core 1 is constructed from a good thermal conductivemetal and placed inside of a cylindrical bushing 8 that has radial heatexchanging fins 9 protruding out in a radial fashion. Said radial heatexchanging fins 9 protruding out of said central core 1 in radialdirection so that surface of said fins 9 is parallel to central axis.The fins 9 may be made spiral-like and bent in the direction ofcentrifugal type impeller rotation (FIGS. 3, 3A).

[0036] The heat exchange channels 10 (FIGS. 3, 3A) are located betweenadjacent radial fins 9. The fins 9 are bent so that the channel widthbetween two adjacent fins 9 is constant.

[0037] A divider 11 placed approximately in the middle of bushing 8divides the air channels in two individual paths, upper path channels 12and lower path channels 13 and upper cylindrical bushing 8A and lowercylindrical bushing 8B. The upper cylindrical bushing 8A along with itsassociated fins 9 and upper path channels 12 form the upper heat sinksection. The lower cylindrical bushing 8B along with its associated fins9 and lower path channels 13 form the lower heat sink section.

[0038] Centered in the top of the core 1 is a radial blower 14 thatincludes a shaft 15, hub 16 and shroud 17 with attached blades 18. Theblades 18 of the radial blower 14 are located around at least part ofthe air outlets 20 and 20A of the channels 12, 13. The divider 11 isplaced as to split the length of the rotor blades 18 substantiallyequally.

[0039] The shroud 17 and the blades 18 of the radial blower 14 aresecured to the hub 16 by means of struts 21. The struts 21 areconstructed in relatively the same shape as the blades of the axial fan23. The shaft 15 of the radial blower 14 is located in a cavity 24 atthe end of the central core 1 and is retained by the bearings 25. Thiscavity 24 may contain a lubricating material that-changes from thickerto thinner state as the core 1 temperature increases. This thinnerlubricant will result in less bearing wear. The shroud 17 of the radialblower 14 has a rounded channel 26. The rotor 27 of the motor 28 issecured in this rounded channel 26. The rotor 26 is shaped like two thincylinders 29, 30 and is made from a permeable magnetic metal. Saidpermeable magnetic material may be different type, preferable is siliconelectric steel.

[0040] The rotor 27 comprises two cylinders 29, 30 and a permanentmagnet 31 located between them. The cylinders 29, 30 have teeth 33 thatface toward the divider 11. These teeth 33 are the actual rotor poles ofthe motor 28 and are magnetized in radial direction, saidcircumferential arrayed like poles of the one magnetized cylinder 29face opposite polarities relative to said circumferential arrayed likepoles of the another magnetized cylinder 30. In the view perpendicularto an axis of rotation, the circumferential arrayed like poles ofmagnetized cylinder 29 about to coincide with the circumferentialarrayed like poles of another magnetized cylinder 30.

[0041] Around an upper part of the fins 9 is located cylindrical bushing36 that secures the stator 37 to the rest of the unit. The stator'scoils are fabricated on standard printed circuit board material (will bedescribed in the second embodiment). The unsecured part of the stator 37is located in a gap formed between the teeth 33 of cylinders 29 and 30.A flat ring 38 is secured on the outside surface of the bottom part ofthe fins 9. The Hall device 39 that may be a Hall sensing element orHall switch (FIG. 7) is used to control commutation of the motor 28. Anoptical device may also be used to control commutation of the motor 28but has limitations because of interference from ambient light sources.The Hall device 39 is located in close proximity to the rotor 303 (FIG.7) and positioned to achieve proper rotational direction and optimumperformance from the motor 28.

[0042] The above describe apparatus functions as follows: When currentis commutated through the stator coils the rotor 27 begins to revolvethe blades 18 of the radial blower 14 around the central core 1 and itsassociated fins 9. The rotating blades 18 pull external airsimultaneously through the upper channels 12 and lower channels 13increasing the cooling ability of the heat sink because of the increasein temperature differentials.

[0043] These channels 12 and 13 may be made of constant width (FIGS. 3,3A). The struts 21, fashioned in relatively the same shape as the axialfan blades 23, provide additional airflow to the upper channel 12improving the overall cooling efficiency.

[0044] The design of the radial blower 14 shown in FIG. 2 was changedfor the purpose of easier assembly. It is comprises a shaft 15, hub 106,shroud 107, and blades 18. These elements are connected to the hub 106through blade shaped struts 202, to form the axial fan 203. The shroud107, with its attached blades 18, is connected to the flat ring 101. Thehub 107 has some holes 310 to allow for ventilation of the stator 37.

[0045] The design of the central core shown in FIG. 2 comprises thespreader 102 being made from high heat conductive metal, usually copper.

[0046] The second embodiment (FIGS. 2-7) differs from the firstembodiment only in that the rotor 207 of the motor is made from twoL-shaped bushings 209, 300. The other components are the same as in thefirst embodiment. Therefore the components the same as described aboveon FIG. 1 are denoted with the same reference numerals, for whichdescription is omitted. These bushings 209, 300 are made from permeablethin metal, preferably silicon electric steel and are secured throughthe flat sides to at least one flat cylindrical permanent magnet 301.The cylindrical parts of the rotor bushings are facing up toward the topflat surface 3 of the core. These cylindrical parts have poles, in theshape of teeth 303 (FIG. 2B). The stator 37 (FIG. 7) of the secondembodiment is relatively the same as the stator of the first embodiment.Stator 37 is formed by an array of printed coils 371 (FIG. 2B). Thesecoils 371 are etched on a flat strip of printed circuit board materialand the board strip is then rolled in the shape of a cylinder. To obtainadditional magnetic strength from the stator coils, a multi-layercircuit board may be used (not shown in the drawings). This allows formore turns on each individual coil.

[0047] The stator coils 371 are constructed so that the width of eachcoil 371 is approximately the same width as each rotor pole 303 (FIG.2B). If necessary the printed circuit board stator 37 (FIG. 2B) can befabricated into separate pieces and then assembled together electricallyand mechanically. Each and every adjacent coil on the stator board isconnected, so when energized they produce opposite magnetic poles whenviewed on the same side of the stator board. The stator coils 371 forthis electric motor 28 are etched using standard circuit boardfabricating means, on standard circuit board materials. The stator ismade from circuit board material having metal layers, preferably copper,and the coil 371 is etched in the metal layers. Said metal layers may beplated by ferromagnetic material (not shown in the drawings). Saidplated ferromagnetic material preferably is nickel.

[0048] The coils are arranged in a linear pattern the length of thecircuit board. Half of one of these coils aligns symmetrically with theVIA connecting the other half coil on the opposite side of the boardwhile maintaining the same turn direction. Each end of this coil is thenseries connected with one of the adjacent coils on the board. Theseadjacent coils are configured such that the current in their turns isflowing in the opposite direction to yield the opposite magneticpolarity. The coils form a continuous series connection with everyadjacent coil having the same turn direction. Each adjacent coil has theopposite magnetic polarity at any one point in time. The beginning andend of the coils on the stator board are used for electrical leadattachment. The stator board is then shaped into a cylinder with the twoends of the stator board adjoined together. The two leads from thestator board attach to a Full Bridge Driver. The sensing element onmotor controller 39 (FIG. 7) uses a Hall Effect Switch or Hall EffectElement to control commutation of the motor. An optical device may alsobe used but has limitations caused by interference from ambient lightsources. The Hall device 39 (FIG. 7) is located in close proximity tothe rotor teeth 303 (FIG. 2) and positioned to achieve proper rotationaldirection and optimum performance from the motor.

[0049] The single ended drive stator boards require a differentlyconstructed stator board. This stator board requires two groups of coils371 (FIG. 2B) wound in the same direction and having common magneticpolarities. The individual coils of one group are series connected andadjacently staggered and spaced between the coils of the other group.One end of each group of coils is connected together and ties to eitherthe positive or negative lead of the motor power supply. If the singleended driver is a Low End Driver, then the connected ends of the coilstie to the positive supply; if a High End Driver then they are connectedto the negative or ground supply. The other end of each of these twogroups ties to the single ended driver. Only one of these groups of thecoils is energized at any one point in time.

[0050] There are many versions of drives with different protectionschemes available, however they all perform essentially the same controlfunction. The Full Bridge Drive has a few advantages over the SingleEnded Drive as can be seen in the following comparison table. Items forComparison Full Bridge Drive Two Phase Single End Drive Stator Boardscoil resistance Equals the sum of all Equals {fraction (1/2 )}the sum ofall seen by Motor Controller individual stator coils individual statorcoils Motor Magnetic Drive Push and Pull Either Push or Pull OperationMotor efficiency More efficient than Two Less efficient than Full BridgePhase Single End Drive Drive Duty Cycle on Stator Board 100% 50% CoilsElectrical Attachment Points 2 3 to Each Stator Board Stator BoardConstruction Requires 1 VIA for each Requires 2 VIA'S for each StatorCoil stator Coil

[0051] Operational Description

[0052] The operation of this cooler for electronic devices will bedescribed using FIG. 1, FIG. 2B and FIG. 7.

[0053] The Hall Switch or Sensor 39 (FIG. 7) supplies a change inelectrical states or levels that are used to operate the full bridgecontroller. These states or levels change in relation to the magneticfields created by the teeth 303 and gaps of the permanent magnet rotor27 (FIG. 1). If the Hall Switch is not aligned with one of the rotorteeth 303 (FIG. 2B), it supplies a voltage output signal that the bridgedriver uses to energize the coils 371 (FIG. 2B) and move the rotorblades toward alignment with the attracting coils on the stator board.Before the rotor teeth 303 reaches the attracting coils the Hall Switchsenses the rotors magnetic field and changes the state of the driverthat causes the rotor teeth 303 to be attracted to the next or adjacentset of coils. Before the rotor teeth 303 reach this set of attractingcoils the Hall Switch senses the loss of the rotor teeth 303 magnetfield and changes the state of the driver causing it to be attracted tothe next set of coils 371. This process continues to maintain a constantmotion in one direction on the rotor.

[0054] The third embodiment (FIG. 8) differs from the second embodimentonly in that the central core 1 comprises an evaporating chamber 7having direct contact with an electronic component heat dissipatingfootprint 6.

[0055] The other components are the same as in the second embodiment.

[0056] The fourth embodiment (FIG. 9) differs from the secondembodiments only in that at least one or several (three) heat pipes 407,408 and 409 are placed inside of the core 308. Each of the three-heatpipes transfers heat energy from separate electronic devices, notillustrated on the drawings. The other components are the same as in thesecond embodiment.

[0057] While the invention has been described with reference to variousembodiments, it will be understood that these embodiments are onlyillustrative that the scope of the invention is not limited to them.Many variations, modifications and improvements of the embodimentsdescribed are possible. Variations and modifications of the embodimentsdisclosed herein may be made based on description set forth herein,without departing from the scope and spirit of the invention as setforth in the following claims.

What is claimed is:
 1. A cooler for electronic devices comprising: aheat exchange element, a blower with a centrifugal type impeller, and anelectric drive, wherein; (i) said heat exchange element comprising acentral part with heat exchanging fins protruding out of said centralpart, and forming channels between adjacent fins for cooling air flow;(ii) said centrifugal type impeller located around at least part of saidheat exchange element and comprising a shroud, connected to a hub placedon bearings secured on said central part of heat exchange element; (iii)said centrifugal type impeller having inner cylindrical space with openend faces to provide intake air through said fins channels from oppositeaxial directions; (iv) said electric drive comprising a magnetic rotorand stator; said magnetic rotor is secured to the centrifugal typeimpeller, said stator of the electric drive is fixed to said heatexchange element.
 2. The cooler for electronic devices as claimed inclaim 1, wherein said electric drive including said magnetic rotor andsaid stator made as a hollow cylinder.
 3. The cooler for electronicdevices as claimed in claim 2 wherein said magnetic rotor comprising atleast two coaxial hollow cylinders, each of said cylinders made as amagnetized cylinder, having circumferential arrayed like poles; saidcircumferential arrayed like poles being magnetized in radial directionand being distributed around an axis of rotation, said circumferentialarrayed like poles of one of said magnetized cylinders spaced from thecircumferential arrayed like poles of another of said magnetizedcylinders in an radial direction to form a cylindrical gap, saidcircumferential arrayed like poles of said one magnetized cylinder faceopposite polarities relative to said circumferential arrayed like polesof said another magnetized cylinder; and wherein in the viewperpendicular to an axis of rotation, said circumferential arrayed likepoles of said one magnetized cylinder about to coincide with saidcircumferential arrayed like poles of said another magnetized cylinder;said stator comprising a coil winding, being, at least partially,coaxially mounted into said cylindrical gap between said circumferentialarrayed like poles of said both magnetized cylinders.
 4. The cooler forelectronic devices as claimed in claim 3 wherein said two hollowcylinders are made from ferromagnetic material, and are magnetized inradial direction by magnet ring installed between them.
 5. The coolerfor electronic devices as claimed in claim 4 wherein said ferromagneticmaterial is silicon electric steel.
 6. The cooler for electronic devicesas claimed in claim 3 wherein said circumferential arrayed like polesare made as teeth at an edge of said magnetized cylinder.
 7. The coolerfor electronic devices as claimed in claim 2 wherein said magnetic rotorcomprising at least two coaxial L-shaped magnetized members, each ofsaid at least two L-shaped members having a magnetized cylinder part anda flat ring bottom part, a magnetized cylinder part havingcircumferential arrayed like poles; said circumferential arrayed likepoles being magnetized in radial direction and being distributed aroundan axis of rotation, said circumferential arrayed like poles of one ofsaid magnetized cylinder part spaced from the circumferential arrayedlike poles of another of said magnetized cylinder part in an radialdirection to form a cylindrical gap, said circumferential arrayed likepoles of said one magnetized cylinder part face opposite polaritiesrelative to said circumferential arrayed like poles of said anothermagnetized cylinder part; and wherein in the view perpendicular to theaxis of rotation, said circumferential arrayed like poles of said onemagnetized cylinder part about to coincide with said circumferentialarrayed like poles of said another magnetized cylinder part; said statorcomprising a coil winding, being, at least partially, coaxially mountedinto said cylindrical gap between said circumferential arrayed likepoles of said both magnetized cylinder parts.
 8. The cooler forelectronic devices as claimed in claim 7 wherein said two members aremade from ferromagnetic material and are magnetized by magnet ring beingmagnetized in axial direction and installed between flat ring bottomparts.
 9. The cooler for electronic devices as claimed in claim 8wherein said ferromagnetic material is silicon electric steel.
 10. Thecooler for electronic devices as claimed in claim 7 wherein saidcircumferential arrayed like poles are made as teeth at an edge of saidmagnetized cylinder part.
 11. The cooler for electronic devices asclaimed in claim 2, wherein said stator are made from circuit boardmaterial having metal layers and a coil winding is etched in the metallayers.
 12. The cooler for electronic devices as claimed in claim 11,wherein said metal layers are copper layers.
 13. The cooler forelectronic devices as claimed in claim 12, wherein said metal layers areplated by ferromagnetic material.
 14. The cooler for electronic devicesas claimed in claim 13, wherein said plated ferromagnetic material isnickel.
 15. The cooler for electronic devices as claimed in claim 2,wherein said stator are round bended circuit board strip having metallayers wherein a coil winding is etched in the metal layers.
 16. Thecooler for electronic devices as claimed in claim 1, wherein said shroudis connected to said hub by brackets making inlet channels for coolingair flow.
 17. The cooler for electronic devices as claimed in claim 16,wherein said brackets comprising blades of axial fan and providedcooling air flow through said fins channels to said centrifugal typeimpeller.
 18. The cooler for electronic devices as claimed in claim 1wherein said central part of said heat exchange element is a cylindricalcentral part.
 19. The cooler for electronic devices as claimed in claim1 wherein said central part of said heat exchange element has a flatbottom for direct contact with an electronic component heat-dissipatingfootprint.
 20. The cooler for electronic devices as claimed in claim 19wherein said flat bottom part of said heat exchange element and saidelectronic component heat dissipating footprint have about the sameshape.
 21. The cooler for electronic devices as claimed in claim 1wherein said central part of said heat exchange element comprising acentral spreader, said central spreader being made from high heatconductive metal.
 22. The cooler for electronic devices as claimed inclaim 1 wherein said central part of said heat exchange elementcomprising an evaporating chamber having direct contact with anelectronic component footprints.
 23. The cooler for electronic devicesas claimed in claim 1 wherein said central part of said heat exchangeelement comprising at least one heat pipe.
 24. The cooler for electronicdevices as claimed in claim 1 wherein said heat exchanging finsprotruding out of said central part in radial direction so that surfaceof said fins is parallel to central axis.
 25. The cooler for electronicdevices as claimed in claim 24 wherein said heat exchanging fins aremade spiral-like and bent in the direction of centrifugal type impellerrotation.
 26. The cooler for electronic devices as claimed in claim 28wherein said spiral-like heat exchanging fins are bent so that channelwidth between two adjacent fins is constant.
 27. The cooler forelectronic devices as claimed in claim 1 wherein at least part of saidheat exchanging fins is surrounded by said centrifugal type impeller.28. The cooler for electronic devices as claimed in claim 1 furthercomprising a flat partition mounted on and perpendicularly to saidcentral part of heat exchange element inside said centrifugal typeimpeller, said flat partition divides said fins in two parts andseparate intake air flows from opposite axial directions.
 29. The coolerfor electronic devices as claimed in claim 1 wherein said bearings ofsaid centrifugal type impeller mounted into said central part of heatexchange element.